TIDEP-0077: 2 microphones usage and the distance between microphones is approx. 10 to 15 mm

Sugawara-san

Here is the guidance we got from the authors of the TI Design

1) LMB has 4 microphones. Is it possible to use only 2 microphones in LMB?

Yes, See codec_pcm186x.h for the NUM_OF_MICS macro. You can use just 2 mics from the 4 if needed.

2) There is small room available on their system. 
     Please let me know if the distance (d0) between microphones is approx. 10 to 15 mm, what are deteriorated from the original demo with 2 microphones and how much.
     The distance between microphones is 21.25 mm for the LMB.

We did not answer this question - perhaps the response to q3 helps 

3) Please let me know the minimum distance between the two microphones. They would like to save the room.

Fundamentally, beam-forming does not work with 2 mics, you need 4+ mics for the BF filters to have an effect.

With 2 mics, its hard to say what the optimal distance is, but you can use the same as the LMB and ensure they are position to face the source of sound better. Enclosure design can also have large impact on audio response quality.

Ensure the noise filtering is also tuned well in software.

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Additionally while the devices on which these TI Designs are based are not auto qualified - you can consider evaluating OMAPL1x family that have auto variants available for select opportunities or you can look at the AM57x family  - technically the designs working on K2G should work well on AM57x family etc. 

Regards

Mukul